Tom Tom - 1 year ago 100
PHP Question

Java & PHP symmetric encryption (DES)

I need to have a basic/simple String encryption (i.e. low security is good enough, I just want to avoid that the communication is human readable) between my Java client application and the PHP server.

I opted thus for the symmetric DES encryption as it doesn't require any key exchange (same key will be used on client and on server) + it doesn't require Java Security Policy updates for longer keys.
I also encode/decode Base64 as the data gets sent by a Http post.

Unfortunately my code doesn't work as decrypted text doesn't match input.

My Java code to encrypt:

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
DESKeySpec keySpecEncrypt = new DESKeySpec(ParamsProvider.SERVER_ECRYPTION_SECRETKEY2); //Secret key is a byte[8] = {1, 2, 3, 4, 5, 6, 7, 8}
SecretKey keyEncrypt = keyFactory.generateSecret(keySpecEncrypt);

// Create the cipher
Cipher desCipher = Cipher.getInstance("DES/CFB8/NoPadding");

// Initialize the cipher for encryption
desCipher.init(Cipher.ENCRYPT_MODE, keyEncrypt);

// Encrypt the text
byte[] textEncrypted = desCipher.doFinal(data.getBytes("UTF-8"));

//B64 encoding and return
byte[] encryptedB64ByteArray = (new org.apache.commons.codec.binary.Base64()).encode(textEncrypted);
return new String(encryptedB64ByteArray, "UTF8");

My PHP code to decrypt:

function decrypt($message) {
$secret_key = array(1, 2, 3, 4, 5, 6, 7, 8);
$decodedMsg = base64_decode($message);
return base64_decode(mcrypt_decrypt(MCRYPT_DES, $key, $decodedMsg, MCRYPT_MODE_CFB));

My best guess is that my Java and PHP en/decryption parameters are not equal (e.g. CFB8 mode) but I have no clue on how to solve this.

Any help or hint would be greatly appreciated (I already lost a few hours on this one),

Tom Tom
Answer Source

Thanks for the hints.

Unfortunately none of them worked out for me.

I finally solved it based on this code:

Cheers, Thomas

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